This invention relates generally to imaging systems capable of operation in multiple modalities, and more particularly to methods and systems for performing a volume computer tomography (CT) scan in a multi-modality system.
Multi-modality imaging systems are capable of scanning using different modalities, such as, for example, Positron Emission Tomography (PET), Single Positron emission tomography (SPECT), Computed Tomography (CT), Static X-Ray imaging, and Dynamic (Fluoroscopy) X-Ray imaging. In a multi-modal system (also referred to as a multi-modality system), a portion of the same hardware is utilized to perform different scans (e.g., an image produced by SPECT is processed and displayed respectively, by the same computer and display, as an image produced by CT). However, the data acquisition systems (also referred to as an “imaging assembly”) are different. For example, on a CT/SPECT system, a radiation source and a radiation detector are used in combination to acquire CT data, while a radiopharmaceutical is typically employed in combination with a SPECT camera to acquire SPECT data.
CT imaging is typically performed using an x-ray source that is collimated into a relatively thin fan-beam of x-rays that radiate from the x-ray source towards a detector. A CT detector is typically a thin linear detector positioned to receive the fan-beam of x-rays radiated by the x-ray source. However, nuclear medicine imaging, such as, but not limited to SPECT imaging is performed using a volume detector wherein a length dimension and a width dimension may be relatively similar. However, even a detector that is capable of imaging both x-ray transmission and gamma ray emission, for example, a CZT detector with a count mode and a high count rate capability, would only use a portion of the CZT detector during a CT portion of a scan.